Traction motor equipped with cooling system and cooling method therefor

Abstract

The present invention relates to the field of traction motors, and specifically provides a traction motor equipped with a cooling system and a cooling method therefor. The traction motor equipped with a cooling system comprises a central rotating shaft, a rotor assembly, and a stator assembly. The rotor assembly is located between the central rotating shaft and the stator assembly. Two axial end portions of the stator assembly and the rotor assembly are each provided with an end cover connected to the central rotating shaft. The cooling system comprises a water cooling system and an air cooling system. The water cooling system is connected to the side of the stator assembly away from the rotor assembly in the circumferential direction. The air cooling system comprises a blade structure located between the rotor assembly and one of the end covers and an air cooling housing located on the outer side of the water cooling system. A cooling air duct is arranged on the air cooling housing. An air outlet and an air inlet are comprised between the end covers and the cooling system. The air outlet and the air inlet are respectively in communication with two ends of the cooling air duct and are in communication with the blade structure. In the present solution, the water cooling structure and the air cooling structure can jointly cool the motor, such that the internal temperature of the motor can be more uniform, thereby reducing the temperature in the interior of the motor and the temperature of each component.

Description

Traction motor with cooling system and cooling method thereof Technical Field

[0001] The present invention relates to the technical field of traction motors, and in particular to a traction motor with a cooling system and a cooling method thereof. Background Art

[0002] With the rapid development of rail transit, performance requirements for traction drives, such as power and economy, have continuously increased. Permanent magnet traction motor technology has begun to be applied in rail transit equipment, placing demands on motors for lighter weight, smaller size, and higher efficiency. Currently, conventional water-cooled permanent magnet traction motors are fully enclosed. Cooling water circulates through a water jacket outside the stator core within the same enclosed space between the stator and rotor. During operation, cooling water flows through the jacket outlet, removing heat from the stator core through heat exchange to cool the motor. This conventional cooling method is difficult to dissipate heat quickly and effectively within the motor. Heat transfer and interaction between the various components within the motor cause temperature increases, and the temperature limits of each component vary, resulting in inadequate motor performance. Therefore, designing the cooling structure of permanent magnet motors to improve cooling and heat dissipation efficiency and enhance motor performance will be a key development direction and technology.

[0003] In order to solve the problem of poor heat dissipation and cooling capacity of permanent magnet motors, a water-cooled permanent magnet motor cooling method has emerged in the existing technical solutions. The water-cooled permanent magnet motor cooling solution is usually a water jacket water-cooling shell and air circulation inside the motor. The water jacket shape is mostly a regular circular structure as shown in Figure 1, where A represents the conventional motor shape structure, B represents the motor available limit range, C represents the axle, and D represents the bottom traction rod. This structure is mainly due to two reasons that make it difficult for conventional water jacket water cooling structures to effectively utilize the bogie space: on the one hand, due to the center distance limitation between the axle and the motor, on the other hand, due to the bottom traction method adopted by the bogie, the motor shape limit is limited, so that when the motor design adopts a conventional water jacket water cooling structure, the bogie space cannot be effectively utilized, resulting in tight available space for the motor and increased difficulty in designing the motor under the same performance requirements. To solve the above problems, in the prior art, there are the following patents involving permanent magnet direct drive motors:

[0004] 1. Patent No. 201921978825.5, entitled "A High-Power Water-Cooled Permanent Magnet Synchronous Motor with a Rotor Air-Cooled Structure," is a utility model patent. The patent comprises a stator housing, a stator core, a rotor core, a rotating shaft, a rotor centrifugal fan, and front and rear end covers. The front and rear end covers are located at either end of the rotating shaft. The rotating shaft is centered on the rotor core, followed by the stator core, stator core, and stator housing. The stator housing is internally provided with a stator air duct and a stator water duct. A rotor air duct is located within the rotor core near the rotating shaft, and a rotor centrifugal fan is located at one axial end of the rotor core. This solution reduces the temperature of the water-cooled permanent magnet motor rotor from the perspective of rotor air cooling, thereby improving the performance of the magnetic steel. This solution can save production costs and achieve stator water cooling and rotor air cooling. However, the rotor air duct is located on the inner side of the rotor core near the rotating shaft, while the permanent magnets are mounted on the outer side of the rotor core near the stator core. This location of the rotor air duct is not conducive to heat dissipation from the permanent magnets, and the bearings at both ends of the motor cannot be effectively cooled.

[0005] 2. The invention patent application with patent application number "202211688822.4" and patent name "A permanent magnet traction motor with built-in axle box" includes a motor base, a stator core, a rotor core, a rotating shaft, bearings, and end caps installed on both sides of the motor base. The inner wall of the motor base is provided with cooling water channels. The motor base is provided with gearbox mounting blocks at the four corners near the drive end. The top of the motor base is provided with a suspension mounting block near the non-drive end. The gearbox mounting block has a mounting hole parallel to the motor axis, and the suspension mounting block has a vertical mounting hole. This solution can achieve lightweight and high power motors, but there is no air circulation inside the motor. Affected by the high temperature of the stator winding end, the temperature inside the motor varies greatly, and the internal temperature of the motor is high.

[0006] In summary, how to design a traction motor and its cooling method with a simple structure, miniaturized design, and the ability to increase the cooling circulation of the gas inside the motor and reduce the internal temperature of the motor is an issue that urgently needs to be addressed.

[0007] Summary of the Invention

[0008] In order to solve the above problems, the present invention provides a traction motor with a cooling system and a cooling method thereof, which can fully utilize the bogie space and increase the cooling circulation of the gas inside the motor through a composite cooling circuit, thereby effectively reducing the temperature of the motor stator and rotor and improving the motor power density and torque density.

[0009] To achieve the above-mentioned purpose, the present invention proposes the following technical solutions: a traction motor with a cooling system, comprising a central rotating shaft, a rotor assembly and a stator assembly, the rotor assembly being located between the central rotating shaft and the stator assembly, and both axial ends of the stator assembly and the rotor assembly being provided with end covers connected to the central rotating shaft; the cooling system comprising a water cooling system and an air cooling system, the water cooling system being circumferentially connected to a side of the stator assembly away from the rotor assembly, the air cooling system comprising a blade structure located between the rotor assembly and the end cover and an air cooling shell located outside the water cooling system, a cooling air duct being provided on the air cooling shell, an air outlet and an air inlet being included between the end cover and the stator assembly, the air outlet and the air inlet being respectively connected to the two ends of the cooling air duct and being connected to the blade structure to form a circulating air path.

[0010] Furthermore, a connecting pressure ring is provided between the water cooling system and the end cover, and the air outlet and the air inlet are both opened on the connecting pressure ring; a ventilation cavity is formed between the central shaft, the stator assembly, the rotor assembly, the end cover, the water cooling system and the connecting pressure ring, the air-cooled outer shell is connected to the outside of the connecting pressure ring and the cooling air duct is connected to the ventilation cavity through the air outlet and the air inlet.

[0011] Furthermore, the end cover includes a non-driving end cover and a driving end cover, the blade structure is arranged in the ventilation cavity on one side of the non-driving end cover, the air outlet is located on the side of the non-driving end cover, and the air inlet is located on the side of the driving end cover.

[0012] Furthermore, a ventilation hole path one communicating with the ventilation cavities on both sides is formed between the rotor assembly and the stator assembly; and at least two ventilation holes communicating with the ventilation cavities on both sides are provided on the rotor assembly.

[0013] Furthermore, the rotor assembly is provided with a second ventilation hole path and a third ventilation hole path connected to the blade structure.

[0014] Furthermore, the water cooling system includes a water-cooling inner shell connected to the stator assembly, a water-cooling outer shell connected to the air-cooling outer shell, and a cooling water channel located between the water-cooling inner shell and the water-cooling outer shell.

[0015] Furthermore, rotor pressing rings pressed onto the central rotating shaft are provided at both axial ends of the rotor assembly, the blade structure is a circulation fan, and the circulation fan is connected to the rotor pressing rings.

[0016] Furthermore, a plurality of water channel ribs are evenly distributed in the cooling water channel and a round-trip water channel is formed by the water channel ribs; a plurality of air channel ribs are evenly distributed in the cooling air channel.

[0017] Furthermore, the overall circumference of the air-cooling housing is smaller than the overall circumference of the water-cooling housing.

[0018] A cooling method for a traction motor with a cooling system, cooling the traction motor, comprising the following steps:

[0019] S1: The circulating fan absorbs the heat generated by the rotor assembly and the stator assembly and transfers the heat to the ventilation cavity on the side of the non-drive end cover;

[0020] S2: The hot air in the ventilation cavity on the non-drive end cover is divided into two paths. The first path of hot air is transported to the ventilation cavity on the drive end cover through ventilation hole path 1. The second path of hot air is transported to the cooling air duct through the air outlet and cooled by the cooling water channel in the cooling air duct. It is then transported to the ventilation cavity on the drive end cover through the air inlet.

[0021] S3: The cooled air in the ventilation cavity on one side of the drive end cover is then transported to the circulation fan through ventilation holes 2 and 3, thereby forming a closed loop of the air path and circulating cooling.

[0022] The beneficial effects of the present invention are: the composite cooling structure composed of an air cooling system and a water cooling system in the present invention can effectively utilize the allowable space of the bogie for the motor to arrange the cooling air duct, and introduce the gas inside the motor into the cooling air duct outside the cooling water channel. The gas inside the motor is cooled by the cooling water channel, water channel ribs, cooling air ducts, and air duct ribs, which can effectively reduce the internal temperature of the motor and the temperature of other components. At the same time, through the circulation of the internal gas, it is also beneficial to reduce the temperature difference of each part and reduce the hot spot temperature. Through the improvement and application of the cooling structure, under the same temperature limit, the shape of the motor can be reduced and the power density and torque density indicators of the motor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic structural diagram of the motor appearance in the background art.

[0024] FIG2 is a schematic diagram of the overall structure of a motor provided by an embodiment of the present invention.

[0025] FIG3 is a schematic structural diagram of a water cooling system and an air cooling system in a motor provided by an embodiment of the present invention.

[0026] Figure numerals: central rotating shaft 1, rotor assembly 2, stator assembly 3, air-cooled casing 4, cooling air duct 5, air outlet 6, air inlet 7, connecting pressure ring 8, ventilation cavity 9, non-drive end cover 10, drive end cover 11, ventilation path one 12, ventilation path two 13, ventilation path three 14, water-cooled inner casing 15, water-cooled outer casing 16, cooling water channel 17, rotor pressure ring 18, circulating fan 19, water channel rib 20, air duct rib 21, water inlet 22, water outlet 23, stator core 24, magnet 25. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is further described below in detail with reference to Figures 2-3 and specific embodiments. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0028] A traction motor with a cooling system, as shown in Figure 2, includes a central rotating shaft 1, a rotor assembly 2, and a stator assembly 3. The rotor assembly 2 is located between the central rotating shaft 1 and the stator assembly 3, and is fixedly connected to the central rotating shaft 1. Both the stator assembly 3 and the rotor assembly 2 are provided with end caps connected to the central rotating shaft 1 at both axial ends. The cooling system includes a water cooling system and an air cooling system. As shown in Figures 2 and 3, the stator assembly 3 includes a stator core 24 and magnets 25. The water cooling system is circumferentially connected to the side of the stator core 24 in the stator assembly 3 away from the rotor assembly 2. The air cooling system includes a blade structure located between the rotor assembly 2 and the end caps, and an air cooling housing 4 located outside the water cooling system.

[0029] The water-cooling system includes a water-cooling inner shell 15 connected to the stator assembly 3, a water-cooling outer shell 16 connected to the air-cooling outer shell 4, and a cooling water channel 17 located between the water-cooling inner shell 15 and the water-cooling outer shell 16. Multiple water channel ribs 20 are evenly distributed within the cooling water channel 17, forming a reciprocating water channel. The water-cooling outer shell 16 is also equipped with a water inlet 22 and a water outlet 23. The air-cooling outer shell 4 is provided with a cooling air duct 5, which is evenly distributed with multiple air channel ribs 21. Due to the limited space outside the motor and the large number of other components, the overall circumference of the air-cooling outer shell 4 is set to be smaller than that of the water-cooling outer shell 16. This ensures the cooling function of the air-cooling system within the limited installation space without interference from other components.

[0030] As shown in Figure 2, an air outlet 6 and an air inlet 7 are included between the end cover and the stator assembly 3. The air outlet 6 and the air inlet 7 are respectively connected to the two ends of the cooling air duct 5 and are connected to the blade structure to form a circulating air path. Specifically, a connecting pressure ring 8 is provided between the two axial ends of the water cooling system and the end cover. The air outlet 6 and the air inlet 7 are both opened on the connecting pressure ring 8. The air-cooled shell 4 is connected to the outside of the connecting pressure ring 8. A ventilation cavity 9 is formed between the central shaft 1, the stator assembly 3, the rotor assembly 2, the end cover, the water cooling system and the connecting pressure ring 8. The cooling air duct 5 is connected to the ventilation cavity 9 through the air outlet 6 and the air inlet 7 to form a circulating air path.

[0031] As shown in Figure 2, the end cover includes a non-drive end cover 10 and a drive end cover 11. The blade structure is arranged in the ventilation cavity 9 on one side of the non-drive end cover 10. The air outlet 6 is located on the non-drive end cover 10, and the air inlet 7 is located on the drive end cover 11. The rotor assembly 2 is provided with a rotor pressure ring 18 at both axial ends, which is pressed against the central shaft 1. The blade structure is a circulation fan 19, which is connected to the rotor pressure ring 18 and is located in the ventilation cavity 9 on the non-drive end cover 10. A ventilation path 12 communicating with the ventilation cavities 9 on both sides is formed between the rotor assembly 2 and the stator assembly 3. The rotor assembly 2 is provided with at least two ventilation paths communicating with the ventilation cavities 9 on both sides. In this embodiment, the rotor assembly 2 is provided with a ventilation path 3 14 and a ventilation path 2 13 communicating with the circulating fan 19. A circulating air path is formed between the ventilation path 12, the ventilation path 3 14, the ventilation path 2 13, the ventilation cavities 9 on both sides, the air outlet 6, the air inlet 7 and the cooling air duct 5.

[0032] A cooling method for a traction motor with a cooling system, for cooling the traction motor, as shown in FIG2 , comprises the following steps:

[0033] S1: The heat generated by the rotor assembly 2 and the stator assembly 3 is absorbed by the circulating fan 19 and transported to the ventilation cavity 9 on the side of the non-driving end cover 10;

[0034] S2: The hot air in the ventilation cavity 9 on the side of the non-driving end cover 10 is divided into two paths. The first path of hot air is transported from the ventilation hole 12 to the ventilation cavity 9 on the side of the driving end cover 11 (the movement path of the first path of air is shown by ① in the figure). The second path of hot air is transported from the air outlet 6 to the cooling air duct 5 and cooled by the cooling water channel 17 in the cooling air duct 5. It is then transported from the air inlet 7 to the ventilation cavity 9 on the side of the driving end cover 11. The two paths of air merge in the ventilation cavity 9 on the side of the driving end cover 11 (the movement path of the second path of air is shown by ② in the figure);

[0035] S3: The cooled wind in the ventilation cavity 9 on one side of the drive end cover 11 is combined and then transported to the circulation fan 19 through the ventilation hole 2 13 and the ventilation hole 3 14, thereby forming a closed loop of the wind path and circulating cooling (the movement path of the wind at the ventilation hole 2 13 is shown by ③ in the figure, and the movement path of the wind at the ventilation hole 3 14 is shown by ④ in the figure).

[0036] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0037] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A traction motor with a cooling system, comprising a central rotating shaft (1), a rotor assembly (2) and a stator assembly (3), the rotor assembly (2) being located between the central rotating shaft (1) and the stator assembly (3), characterized in that, End caps are provided at both axial ends of the stator assembly (3) and the rotor assembly (2) and are connected to the central rotating shaft (1); the cooling system includes a water cooling system and an air cooling system. The water cooling system is circumferentially connected to the side of the stator assembly (3) away from the rotor assembly (2). The air cooling system includes a blade structure located between the rotor assembly (2) and the end cap and an air cooling housing (4) located outside the water cooling system. A cooling air duct (5) is provided on the air cooling housing (4). An air outlet (6) and an air inlet (7) are included between the end cap and the stator assembly (3). The air outlet (6) and the air inlet (7) are respectively communicated with both ends of the cooling air duct (5) and are communicated with the blade structure to form a circulating air path.

2. The traction motor with a cooling system according to claim 1, characterized in that, A connecting retaining ring (8) is provided between the water cooling system and the end cap. The air outlet (6) and the air inlet (7) are both provided on the connecting retaining ring (8); a ventilation cavity (9) is formed among the central rotating shaft (1), the stator assembly (3), the rotor assembly (2), the end cap, the water cooling system and the connecting retaining ring (8). The air cooling housing (4) is connected to the outside of the connecting retaining ring (8), and the cooling air duct (5) is communicated with the ventilation cavity (9) through the air outlet (6) and the air inlet (7).

3. The traction motor with a cooling system according to claim 2, characterized in that, The end cap includes a non-drive end cap (10) and a drive end cap (11). The blade structure is arranged in the ventilation cavity (9) on one side of the non-drive end cap (10). The air outlet (6) is located on one side of the non-drive end cap (10), and the air inlet (7) is located on one side of the drive end cap (11).

4. The traction motor with a cooling system according to claim 3, characterized in that, A first ventilation hole path (12) communicating with the ventilation cavities (9) on both sides is formed between the rotor assembly (2) and the stator assembly (3); at least two ventilation hole paths communicating with the ventilation cavities (9) on both sides are provided on the rotor assembly (2).

5. The traction motor with a cooling system according to claim 4, characterized in that, A second ventilation hole path (13) and a third ventilation hole path (14) communicating with the blade structure are provided on the rotor assembly (2).

6. The traction motor with a cooling system according to claim 5, characterized in that, The water cooling system includes a water cooling inner shell (15) connected to the stator assembly (3), a water cooling outer shell (16) connected to the air cooling housing (4), and a cooling water channel (17) located between the water cooling inner shell (15) and the water cooling outer shell (16).

7. The traction motor with a cooling system according to claim 6, characterized in that, Rotor retaining rings (18) are provided at both axial ends of the rotor assembly (2) and are pressed tightly on the central rotating shaft (1). The blade structure is a circulating fan (19), and the circulating fan (19) is connected to the rotor retaining ring (18).

8. The traction motor with a cooling system according to claim 7, characterized in that, A plurality of water channel ribs (20) are evenly distributed in the cooling water channel (17), and a reciprocating water channel is formed through the water channel ribs (20); a plurality of air duct ribs (21) are evenly distributed in the cooling air duct (5).

9. The traction motor with a cooling system according to claim 8, characterized in that, The overall circumference of the air cooling housing (4) is smaller than the overall circumference of the water cooling outer shell (16).

10. A cooling method for a traction motor with a cooling system, which cools the traction motor according to any one of claims 7-9, characterized in that, Including the following steps: S1: The circulating fan (19) absorbs the heat generated by the rotor assembly (2) and the stator assembly (3) and transports the heat into the ventilation cavity (9) on one side of the non-drive end cap (10); S2: The hot air in the ventilation cavity (9) on one side of the non-driving end cover (10) is divided into two paths. The first path of hot air is transported through the first ventilation hole path (12) into the ventilation cavity (9) on one side of the driving end cover (11). The second path of hot air is transported through the air outlet (6) into the cooling air duct (5) and is cooled by the cooling water duct (17) in the cooling air duct (5), and then is transported through the air inlet (7) into the ventilation cavity (9) on one side of the driving end cover (11). S3: The cooled air in the ventilation cavity (9) on one side of the driving end cover (11) is then transported to the circulation fan (19) through the second ventilation hole path (13) and the third ventilation hole path (14), thereby forming a closed loop of the air path and circulating for cooling accordingly.

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